Bismuth-210 is a radioactive isotope of the element bismuth, which has the atomic number 83. It is produced through the decay of polonium-210 and has a half-life of about 5.01 days. This means that after this time, half of a sample of bismuth-210 will have decayed into another element, lead-210. Bismuth-210 emits beta particles during its decay process, making it useful in certain scientific and medical applications. It is often studied in the context of environmental monitoring and radiation safety, as well as in research related to nuclear physics and radiochemistry.